﻿// --------------------------------------------------------------------------------------------------------------------
// <copyright file="DnsServer.cs" company="Rolosoft Ltd">
//   © Rolosoft Ltd
// </copyright>
// --------------------------------------------------------------------------------------------------------------------

#region License

// Copyright 2013 Rolosoft Ltd
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
// http://www.apache.org/licenses/LICENSE-2.0
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#endregion

namespace Rsft.Net.Dns.Helpers
{
    #region Usings

    using System.Collections.Generic;
    using System.Collections.ObjectModel;
    using System.Net;
    using System.Net.NetworkInformation;

    #endregion

    /// <summary>
    /// The DNS server helper.
    /// </summary>
    public static class DnsServer
    {
        #region Constants

        /// <summary>
        /// The default port.
        /// </summary>
        private const int DefaultPort = 53;

        #endregion

        #region Public Properties

        /// <summary>
        /// Gets the local default DNS servers.
        /// </summary>
        public static IEnumerable<IPEndPoint> LocalDefaultDnsServers
        {
            get
            {
                var list = new List<IPEndPoint>();

                var localAdapters = NetworkInterface.GetAllNetworkInterfaces();
                foreach (NetworkInterface adapter in localAdapters)
                {
                    if (adapter.OperationalStatus == OperationalStatus.Up)
                    {
                        var props = adapter.GetIPProperties();

                        foreach (IPAddress address in props.DnsAddresses)
                        {
                            var entry = new IPEndPoint(address, DefaultPort);
                            if (!list.Contains(entry))
                            {
                                list.Add(entry);
                            }
                        }
                    }
                }

                return new ReadOnlyCollection<IPEndPoint>(list);
            }
        }

        #endregion
    }
}